Magnetic core structures



3 Sheets-Sheet l :l L r l INVENToR Curtls L. Moore BY MF( ATTORNEY C. L. MOORE MAGNETIC GORE STRUCTURES Fig.|.

June 15, 1965 Filed Jan. 11, 1961 June 15, 1965 c. MOORE MAGNETIC CORE STRUCTURES Filed Jan. l1, 1961 3 Sheets-Sheet 2 June 15, 1965 c. L.. MOORE 3,189,858

MAGNETIC CORE STRUCTURES Filed Janll, 1951 5 Sheets-Sheet 3 United States Patent O 3,139,858 MAGNETIC CURE STRUCTURES Curtis L. Moore, Sharon, Pa., assignor to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation of Pennsylvania Filed Jan. 11, 1961, Ser. No. 32,1126 Claims. (El. 336-212) This invention relates to electrical inductive apparatus, such as reactors or transformers, and more particularly to magnetic core structures for such apparatus.

In a conventional construction of magnetic cores employed in certain types of electrical inductive apparatus, such as reactors or preventive autotransformers, the different portions of the magnetic core which may be either of the wound type or the stacked type are first assembled and then held in assembled relationship by the use of separate tie rods. A conventional construction of the latter type has several disadvantages, particularly where the magnetic core includes a plurality of gaps. For example, a conventional tie rod must be fabricated or designed for each application. In addition, a conventional magnetic core of this type employs a large number of parts and ditlerent sizes of parts which do not lend themselves to convenient assembly. Further, a conventional magnetic core of the above type may be an undesirable source of noise during operation. It is therefore desirable to provide an improved magnetic core structure of the above type which includes portions both of the stacked type and the wound type and an improved means for maintaining said portions in assembled relationship.

It is an object of this invention to provide a new and improved magnetic core structure for electrical inductive apparatus.

Another object of this invention is to provide a newV and improved core and coil assembly for electrical inductive apparatus, such as reactors and transformers.

A further object of this invention is to provide a new and improved means for maintaining the different portions of a magnetic core structure in assembled relationship.

A more specific object of this invention is to provide a new and improved magnetic core structure for a reactor or autotransformer which includes a plurality of gaps therein.

Other objects of the invention will, in part, be obvious and will, in part, appear hereinafter.

For a fuller understanding of the nature and objects of the invention, reference should be had to the following detailed description taken in connection with the accompanying drawings, in which:

FIGURE 1 is a front elevational View of a reactor core and coil assembly embodying the teachings of the invention;

FIG. 2 is a side elevational view in section of the core and coil assembly shown in FIG. 1, taken along the line II-llg FIG. 3 is a partial View, in elevation, of the magnetic core included in the core and coil assembly shown in FIG. 1 illustrating the arrangement of the gaps therein;

FIG. 4 is a partial View in section of the magnetic core included in the core and coil assembly shown in FIG. 1 illustrating how certain laminations included in said magnetic core are held in assembled relationship;

FIG. 5 is a top plan view, partly in section, of the core and coil assembly shown in FIG. 1;

FIG. 6 is a partial View in section illustrating an alternative construction of a magnetic core included in the core and coil assembly shown in FIG. l; and

FIG. 7 is a partial schematic diagram illustrating an application of the reactor core and coil assembly shown in FIG. 1.

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Referring now to the drawings and FIGS. l, 2 and 5 in particular, there is illustrated a reactor core and coil assembly 1t) embodying the teachings of the invention. In general, the core and coil assembly 19 comprises the magnetic core structure 2t) on which are inductively disposed the first and second winding sections or coils 30A and 30B, respectively. The magnetic core structure 2d and the winding sections 30A and 38B are supported by a base or bed plate member 92, which in turn rests on the channel members 94. The magnetic core structure 20, which is illustrated as being of the core form type, includes the first and second leg portions L1 and L2, respectively, which are disposed in parallel with one another and spaced apart from one another, and the upper and lower yoke portions Y1 and Y2, respectively, which connect the ends of said leg portions and which are assembled with said leg portions around a substantially rectangular window to form a closed magnetic path or loop.

More specifically, the upper and lower yoke portions or members Y1 and Y2., respectively, of the magnetic core structure 2t), which are of the stacked type, each comprises a plurality of laminations or punchings which are formed from magnetic strip or sheet material and assembled in a substantially rectangular configuration. The magnetic strip material from which the laminations of the upper and lower yoke portions Y1 and Y2, respectively, are formed may be of any suit-able type, such as coid-rolled silicon steel which has a more favorable direction of orientation or easier magnetization substantially` parallel to its edges for longitudinal dimension and has a coating of electrical insulating material, such as Carlite (magnesium phosphate), on at least one side thereof to reduce the current losses in the mgnetic core structure 20. The laminations of the upper and lower yoke portions Y1 and Y2, respectively, which are substantially rectangular in shape are assembled or stacked to provide iirst and second openings or holes 199 and 299, respectively, therethrough, as best shown in FIGS. 2 and 5 for reasons which will be explained hereinafter. The openings 199 and 299 at the opposite ends of each of the yoke portions Y1 and Y2 pass through said yoke portions in a direction which is substantially parallel to the surface of each of the laminations, which make up said yoke portions. The openings 199 yand 299 of each of the yoke portions Y1 and Y2 are displaced from one another along a central axis of each of said yoke portions.

In order to maintain the laminations of the upper and lower yoke portions Y1 and Y2, respectively, in assembled relationship, the clamping plates 192 and 194 are provided on opposite sides of the upper and lower yoke portions Yil and Y2, respectively. The clamping bolt and nut means 132, 133 are provided for the upper yoke portion Y1 while Ishe clamping b'olt and nut means 184, 185 are provided for the lower yoke portion Y2. In order to prevent shorting of the laminations of the upper and lower yoke portions Y1 and Y2 respectively by the bolts 182 and 184 respectively, each of said bolts passes through the laminations of the associated yoke portion and the associated clamping plates through an electrically insulating tube or sleeve member, as indicated at 136 in FIG. 4 for the lower yoke portion Y2. In addition, the clamping plates 192 and 194 associated with the upper and lower yoke portions lfd and Y2 respectively are insulated from the laminations of the upper and lower yoke portions Y1 and Y2, respectively, by the electrically insulating members 86 and 198, respectively. The laminations of the lower yoke portion Y2 are also insulated from the base member 92, which would normally be formed from a suitable metallic material, by the electrically insulating member 196, as best shown in FIG. 2.

In order to permit lifting of the core and coil assembly 10 by separate lit-ting means, the iirst and second lifting members or lugs 52 and 54, respectively, are secured to the upper yoke portion Yi, as best shown in FIGS. 2 and 5. In particular, the lifting members 52 and 54 are secured to the upper yoke portion YI by the clamping bolt and nut means iZ, 183 and form with the associated yoke frame members 53 two generally U-shapedupper yoke end frame members which are displaced from each other along the upper yoke portion Y1. The clamping bolts 1&2 pass through the depending portions oi the first and second lifting members 52 and 54, respectively, and their associated yoke frame members 53, In order to insulate the laminations of the upper yoke portion Yili from the lifting members 52 and 545 and the yoke frame members 53, the electrically insulating members or pieces 88 are provided between said laminations and said lifting members and said yoke frame members.

Referring now to FIGS. 2 and 5 in particular, each of the leg portions Ll and L2 of the magnetic core structure 2@ comprises a plurality of stacked ring type or toroidal magnetic core sections 72 through S0, each having a central opening or hole therethrough `and a radial gap which extends aiXally therethrough, as indicated at GI for the toroidal or annular core section 72 in FIG. 5, to reduce lossses due to circulating currents or eddy currents which might otherwise result. Each of the core sections 7-2 through 3Q of the leg portions L1 and L2 may be formed by winding a plurality of turns of magnetic strip material on an associated mandrel and then bonding said turns together by a suitable bonding or adhesive material, which may be a thermosetting resin, such as a phenolic resin or epoxy, which is also an electrically insulating material. Examples of suitable core bonding materials are disclosed in US. Patent 2,372,074 which was filed by l. G. Ford and assigned to the same assignee as the present application. After the turns of each of the ring core sections 72 through 80 have been bonded together to prevent relative movement of said turns, each of the core sections 72 through 4Sti may be cut by a saw to provide a radial gap which extends axially therethrough, as indicated at Gi for the core section 72 in FIG. 5, and as indicated at G2 and G3 for the core sections 74 and 76, respectively in FIG. 3 and to provide a plurality of separate laminations of magnetic material in each of said core sections. The magnetic strip or sheet material from which the laminations of each of the core sections 72 through Sii are formed maybe the same as the magnet-ic material from which the laminations of the yoke portions Yi and YZ are formed or it may also be hot-rolled silicon steel which has a random magnetic orientation. The magnetic strip ma,- terial from which the laminations of the ring sections 72 through titi are formed would also have a coating of electrically insulating material on at least one side thereof, such as Carlite, to reduce eddy current losses in the leg portions Li and L2.

As best shown in FIG. 2, the core sections '72 through Si) of each of the leg portions LI and LZ are assembled or stacked adjacent to one another along a common central axis, which is substantially vertical, with the central openings of the core sections 72 through Si? in each of the leg portions LI and L2 substantially aligned with one another and with the corresponding openings i953 and 2% in the upper and lower yoke portions Yil and YZ, respectively, for reasons which Vwill be explained hereinafter. In order to provide a plurality of axial gaps in each of the leg portions Ll and L2, the spacing members Si are disposed between each of the adjacent core sections 72 through 89 of each of said leg portions. The spacing members Si each includes a central opening slightly larger than the central openings in the associated core sections 72 through 8@ and may be formed from a suitable electrically insulating material, such as a laminated plastic material, which is also non-magnetic. As shown in greater detail in FIG. 3, the rst and second gasket members are disposed on opposite sides of each of the spacing members Si for reasons which will be described hereinafter.

Each of the relatively thin washer-shaped gasket members 49, which includes a central opening, may be formed from a suitable electrically insulating material similarly to the spacing members 5l in order to prevent shorting oi the laminations in the adjacent core sections, iIn order to prevent shorting o-f the 'laminations in the upper and lower yoke portions Y1 and Y2 respectively by the laminations in the adjacent core sect-ions 72 and Si?, respectively, or the converse, the electrically insulating members 87 which are relatively thin and washer-shaped in configuration are provided between the yoke portions Yi and Y2 and the adjacent core sections 72 and Si?, respectively, as best shown in FIG. 2.

In order to maintain the different portions of the magnetic core structure 2t) in assembled relationship with espect to one another and to secure the magnetic core structure 2@ to the base member 92, 'the cast or molded supporting members l5@ are provided. Each of the elongated supporting members passes through and substantially fills one of the openings 199 and 299 in the upper yoke portion Y1, through the central openings of the ring sections 72 through 39 in one of the leg portions Li and L2, through one of the openings 199 and 299 in the lower yoke portion Y2 and through one of the aligned openings or holes 97 provided in the base member 92 to lill the cup-shaped members 96 which are secured to the underside of the base member 92 around the openings 97 in said base member. The supporting member i5@ also includes a plurality of integral radially projecting portions 150A which extend into the radial gaps of the core sections 72 through 8i) of the leg portions L1 and LZ, as indicated at G1 for the core section 72 in FIG. 5 and as indicated at G2 and G3 for the core sections 74 and 76, respectively in FIG. 3. Each of the supporting members I5@ is formed by passing a reinforcing brous or larnentary material, such as glass rope or yarn, through each of the openings 199 and 299 in the upper and lower yoke portions YI and Y2, respectively, and the corresponding central openings in the ring sections 72 through Si? of each of the leg portions L1 and L2 and then filling the balance of the space in said openings and in the radial gaps of said core sections with a suitable thermosetting resin, such as an epoxy resin or polyester resin, which is then cured or polymerized in place to bond the different portions of the magnetic core structure 2t) together in a unitary assembly and to secure the magnetic core structure 2i? to the base member 92. Y In order to facilitate the alignment of the diiierent portions of the magnetic core structure 2t) during the assembly thereof, the centering or positioning pins 9S may be provided in the cup-shaped members 96 to cooperate with a temporary alignment rod (not shown) during the assembly of said portions. When a temporary rod of the latter type is employed, it may be removed before the thermosetting resin is introduced into the openings of the different portions of the magnetic core structure 2Q or may be left in place in a particular application.

As best shown in FIGS. 2 and 5, the winding sections or coils SQA and 319B are inductively disposed on the leg portions LI and L2, respectively, of the magnetic core structure 2i?. Each of the winding sections 36A and 39B comprises a plurality of turns of conducting sheet or strip material which is spirally wound together with an insulating sheet material having at least a partial coating of a thermosetting resin, such as an epoxy resin, thereon around the electrically insulating tubular member or winding form 152 which additionally insulates said winding sections from the leg portions L?. and L2, respectively. The thermosetting resin included in each of the winding sections 36A and 36B is then cured in place to bond the turns of said winding sections together in unitary members and to prevent relative movement of the turns of said winding sections with respect to one another without requiring separate bracing or end frameV structures in the core and coil assembly It?. In order to provide cooling ducts between the Winding forms 152 and the leg portions L1 and L2 through which an associated cooling medium, such as insulating oil, may pass to carry on the heat which results in the leg portions L1 and L2 due to losses therein, the spacing members 154 may be disposed between the winding forms 152 and the leg portions L1 and L2. The spacing members 154 may be formed from a suitable electrically insulating iibrous material and may be bonded to both the leg portions L1 and L2 and the associated winding forms 152 by a suitable bonding material, such as a thermosetting resin. In certain applications, the turns of the winding sections 39A and 313B may be Wound directly on the leg portions L1 and L2 which are substantially circular in cross section since the magnetic strip material from which the lamniations of said leg portions are formed would normally have an electrically insulating coating on at least one side thereof. It is also to be understood that the winding sections 30A and 30B may be formed from turns of a conducting sheet material having a coating of electrically insulating material, such as an insulating enamel, on at least one side thereof, said turns being bonded together by a suitable bonding material, such as a thermosetting resin, to eliminate the need for a separate insulating sheet material in said winding sections. i

In order to provide means for making external connections to the winding sections SA and 30B, the terminal board 44 which is formed from a suitable electrically insulating material, such as pressboard, is disposed on the upper portion of the core and coil assembly 10. In partisular, the terminal board 44 is supported or mounted on the supporting or bracket members 62, which in turn are secured to the upper yoke portion Y1 by the clamping bolts 182, as best shown in FIG. 2. The conductor studs or terminal members P1, P2 and P3 are mounted or disposed in spaced relationship on the terminal board 44. rhe innermost conductor turn of the winding section 30A, as indicated at C1, is electrically connected to the depending portion 131 of the terminal member P1 by the flexible conductor 121, while the innermost conductor turn of the winding section 39B, as indicated at C3, is electrically connected to the depending portion 133 of the terminal member P3 by the iiexible conductor 123. The outermost conductor turns of each of the winding sections 39A and 39B, as indicated at C4 and C2, respectively, are both connected to the conducting member 124 which in turn is electrically connected to the depending portion 132 of the terminal member P2 by the exible conductor 122. As indicated schematically in FIG. 7, therefore, the terminal member P2 effectively becomes the mid-tap connection of the winding sections 39A and 30B considered together as a single overall winding.

Referring now to FIG. 6, there is illustrated an alternative supporting member 251i which may be substituted for the supporting member 151i in the core and coil assembly lll in certain applications. In general, the supporting member 251i is similar to the supporting member 159 previously described except that the supporting member 259 additionally includes a plurality of projecting portions 259A which extend radially into the spaces between the core sections 72 through Sil of each of the leg portions L1 and L2 to eliminate the need for separate spacing members such as the spacing members 51 shown in FIGS. 2 and 3. In the modied construction of the supporting member 259 shown in FIG. 6, a plurality of spacing or gasket members 75 are disposed between the adjacent core sections 72 through titl of each of the leg portions L1 and L2 at the outer periphery thereof. The annular gasket members 75 may be formed from any suitable electrically insulating material, such as neoprene rubber, which is also non-mag netic and may be either rectangular or substantially circular in cross section. In other respects, the supporting member 25o may be formed similarly to the supporting member 150 previously described in detail. It is to be noted that the gasket members 49 in the core and coil assembly 10 and the gasket members 75, shown in FIG. 6, eiectively seal off the spaces between the core sections 72 through 80 of each of the leg portions L1 and L2 to prevent the escape of any thermosetting resin which is introduced into the central openings of said core sections during the forming of the supporting members 159 or 250.

In one preferred method of producing the core and coil assembly 10, the laminations of the lower yoke portion Y2 are first assembled or stacked as shown in FIG. 2 with the openings 199 and 299 aligned in a vertical direction on top of the base member 92. The core sections 72 through S0 of the leg portions L1 and L2 are then stacked vertically on the lower yoke portion Y2 with the central openings of the core sections of each of said leg portions substantially aligned with the corresponding openings 199 and 299 in the lower yoke portion Y2. During the stacking of the core sections 72 through 8i), which make up each of the leg portions L1 and L2, the radial gaps included in the ring sections which make up each of said leg portions may be conveniently aligned along a vertical line in each of said leg portions and then closed oit by a suitable sealing strip or tape. Next, the winding sections 30A and 39B may be assembled on the leg portions L1 and L2, respectively, with the spacing members or duct formers 154 wedged between the winding forms 152 and the leg portions L1 and L2. The laminations of the upper yoke portion Y1 may then be assembled on -top of the leg portions L1 and L2 with the openings 199 and 299 of the upper yoke portion Y1 substantially aligned with the central openings in the leg portions L1 and L2, respectively. It is to be noted that during the stacking of the ring sections 72 through Si! that the spacing members 51 may be alternately disposed or stacked between said core sections or that gasket members similar to the gasket member '75 shown in FIG. 6 may be alternately disposed between said core sections. Next, a reinforcing fibrous or lilamentary material 79, such as glass, yarn or rope, is passed through each of the openings 199 and 299 in the upper yoke portion Y1 and through the central openings of the core sections which malte up each of the leg portions Ll and L2 and through the openings 199 and 299 in the lower yoke portion Y2 into the cup-shaped members 96. A suitable thermosetting resin, such as an epoxy resin, is then poured or introduced into the openings 199 and 299 ot the upper yoke portion to substantially till the balance of the spaces in the openings of the upper and lower yoke portions Y1 and Y2, respectively, and the central openings of the ring core sections which make up each of the leg portions L1 and L2, as well as the radial gaps in said core sections. Finally, the thermosetting resin is cured or polymerized in place to form the supporting members 1513 or 251i and bond the different portions of the core and coil assembly lil together into a unitary member, as well as to secure the magnetic core structure Ztl of said core and coil assembly to the base member 92. It is to be noted that the different portions of the magnetic core structure 20, as well as the cup-shaped members 96 of the base member 92, form two separate vessels or molds into which the thermosetting resin may be poured to form the supporting members 15@ or 250. As previously mentioned, where the gasket members are employed, the thermosetting resin, which is poured in the manner just described, extends radially into the spaces between the core sections 72 through Sti of the leg portions L1 and L2 to eliminate the need for separate spacing members, such as the spacing members 51 shown in FIGS. 2 and 3. It is to be understood that the thermosetting resin included in the winding sections 39A and 30B may be cured simultaneously with the thermosetting resin included in the supporting members or 250 for convenience during manufacture.

andasse Referring now to FIG. 7, there is illustrated a typical application of the core and coil assembly lt) with an associated tap changing transformer lttl which may be of any conventional type. As illustrated, the tap changing transformer litt? includes a primary winding l28 and a secondary winding 13@ having a plurality of tap connections lli, said primary and secondary windings being inductively disposed on an associated magnetic core structure liti. The transformer le@ is also provided with the tap changing equipment 12d, having the selector switches Sl and S2. As shown in FiG. 7, the core and Vcoil assembly liti may be employed with the tap changing equipment lZti to limit the circulating current which would otherwise liow whenever the selector switches Sl and SZ are connected to adjacent tap connections ll?, in the bridging position.

lt is to be understood that the teahings of the invention may be embodied in other types of single phase or three-phase magnetic core structures including two or more leg portions, such as the leg portions Ll and L2, having the ends connected by upper and lower yoke portions of the type disclosed. It is also to be understood that the bonding between the yoke portions and the leg portions in the magnetic core structure disclosed may be varied by proper selection of the thermosetting resin and the reinforcing material which forms part of the supporting members 15d or 25d to thereby reduce the sound level of the core and coil assembly in which the magnetic core structure is employed. lt is to be noted that the bonding action provided by a supporting member as disclosed may be designed to prevent any change in the characteristics of the magnetic core structure due to the magnetic forces present during the operation of the lcore and coil assembly lil.

The apparatus embodying the teachings of this invention has several advantages. For example, a core and coil assembly as disclosed lends itself to convenient assembly during manufacture and avoids the necessity for specially designed tie rods and tie plates in each application to hold the different portions of the core and coil assembly in a predetermined relationship. In addition, a core and coil assembly including winding sections formed from turns of conducting strip material as disclosed eliminates the requirement for separate end frame structures or bracing means to maintain the turns of the winding in assembled relationship and to prevent relative movement of said turns. Further, a core and coil assembly employing a unitary supporting member as disclosed eliminates the requirement of a large plurality of specially designed insulation pieces and members. One inalradvantage that a magnetic core as disclosed has over a conventional magnetic core, particularly one of the stacked type, is a lower sound or noise level during operation. This results from the bonding action in the different portions of the disclosed magnetic core which substantially eliminates the chatter that might otherwise result.

Since numerous changes may be made in the above described apparatus Vand method and different embodiments of the invention may be made without departing from the spirit and scope thereof, it is intended that all `the matter contained in the foregoing description or shown in the accompanying drawings shall be interpreted as illustrative and not in a limiting sense.

l claim as my invention:

l. A magnetic core structure comprising first and second leg portions spaced apart from one another, yoke portions connecting the ends of said leg portions, each of said yoke portions comprising a plurality of laminations formed from magnetic strip material and assembled in a rectangular configuration having first and second openings therethrough, each of said leg portions comprising a plurality of ring core sections, each of said ring core'sections including a central opening and a radial gap extending axially thorugh said section, the ring core sections of each leg portion being assembled between the associated yoke portions along a common axis with the central openings substantially aligned with each other and with one of the openings in each of said yoke portions, annular electrically insulating members disposed between the adjacent ring coreV sections, each insulating member having an opening therethrough larger than the opening in each ring core section, fibrous reinforcing material disposed to pass through the aligned openings of each leg portion and the associated yoke portions, a thermosetting resin filling the'balance of the aligned openings and the radial gaps of said ring core sections and the openings in the insulating members to bond said yoke and leg portions and said insulating members together in a unitary assembly, and said resin having projecting portions formed around its periphery in the openings in the insulating members.

2. A magnetic core comprising first and second leg portions disposed in parallel with one another and spaced apart, yoke portions connecting the ends of said leg portions, said yoke portions each comprising a plurality of laminations formed' from magnetic strip material and assembled to provide a rectangular member having first and second openings therethrough parallel to the edges of said strip material, said leg portions each comprising a plurality of cylindrical core sections each having a central opening and a radial gap extending axially therethrough, said core sections each including a plurality of laminations formed from magnetic strip material, the core sections of each leg portion being stacked between said yoke portions with the central openings substantially aligned with each other and with one of the openings in each yoke portion, annular spacing members disposed between adjacent core sections in each leg portion at the outer periphery thereof, each spacing member having an opening therethrough larger than the opening in each core section, filamentary reinforcing material disposed to pass through the aligned openings of each leg portion and the associated yoke portions, and a resinous binder disposed to fill the rest of the openings in said yoke portions and the central openings in said leg portions to bond said yoke and leg portions and said spacing members together in a unitary assembly, said resinous binder extending radially outward from said central openings to substantially fill the radial gaps and to provide projecting portions on the binder in th spaces between `said cylindrical core sections.

3. A reactor comprising a base, a magnetic core having first and second parallel yoke portions disposed apart from one another, a plurality of leg portions disposed between said yoke portions and spaced from one another, said yoke portions each including a plurality of laminations formed from magnetic strip mater-ial to provide a rectangular member having an opening therethrough associated with each leg portion, said leg portions each including a plurality of annular core sections each having a central opening and a radial gap extending axially therethrough, the core sections of' each leg portion being assembled along a common axis with the central openings substantially aligned with each other and with the associated openings in said yoke portions, said base having openings therein aligned with the openings in the yoke portions, retaining means around the openings in the base, a thermosetting resin substantially lling the aligned openings in said yoke and leg portions and the gaps in said leg portions and said retaining means to bond the yoke and leg portions together in a unitary assembly and to secure the assembly to the base by an enlarged portion formed in said retaining means, and an electrical winding inductively disposed on each of said leg portions, said winding comprising a plurality of spirally wound turns of a first layer of conducting sheet material and a second layer of insulating sheet material having at least a partial coating of thermosetting resin thereon, the thermosetting resin on said insulating sheet material bonding the turns of said winding together in a unitary assembly.

4. A reactor comprising a base, a magnetic core having rst and second parallel yoke portions disposed apart from one another, a plurality of leg portions disposed between said yoke portions and spaced from one another, said yoke portions each including a plurality of laminations formed from magnetic strip material to provide a rectangular member having an opening therethrough parallel to the edges of said strip material associated With each leg portion, said leg portions each including a plurality of annular core sections each having a plurality of laminations of magnetic strip material arranged with a central opening and a radial gap extending axially therethrough, the core sections of each leg portion being assembled along a common axis with the central openings substantially aligned with each other and with the associated openings in said yoke portions, said base having openings therein aligned With the openings in the yoke portions, generally cup-shaped means around the openings in the base, reinforcing ilamentary material disposed to pass through the aligned openings in said yoke and leg portions, a thermosetting resin substantially filling the openings in said yoke and leg portions and the gaps in said leg portions and said cup-shaped means to bond the yoke and leg portions together in a unitary assembly and to secure the assembly to the base by an enlarged portion formed in said cup-shaped means, and an electrical Winding inductively disposed on each of said leg portions, said winding comprising a plurality of spirally Wound turns of a rst layer of conducting sheet material and a second layer of insulating sheet material having at least a partial coating of thermosetting resin thereon, the thermosetting resin on said insulating sheet material bonding the turns of said Winding together in a unitary assembly.

5. A reactor comprising a base, a magnetic core having first and second parallel yoke portions disposed apart from one another, a plurality of leg portions disposed between said yoke portions and spaced from one another, said yoke portions each including a plurality of laminations formed from magnetic strip material to provide a rectangular member having an opening therethrough associated with each leg portion, said leg portions each including a plurality of annular core sections each having a central opening and a radial gap extending axially therethrough, the core sections of each leg portion being assembled along a common axis with the central openings substantially aligned with each other and with the associated openings in said yoke portions, said base having openings therein aligned with the openings in the yoke portions, generally cup-shaped means attached to the base around the openings in the base, spacing members disposed between the adjacent annular core sections of each leg portion at the outer periphery thereof, reinforcing fibrous material disposed to pass through the aligned openings in said yoke and leg portions, a thermosetting resin substantially filling the openings in said yoke and leg portions and the spaces between said annular core sections and the gaps in said leg portions and said cupshaped means to bond the yoke and leg portions together in a unitary assembly and to secure the assembly to the base by an enlarged portion formed in said cup-shaped means, and an electrical winding inductively disposed on each of said leg portions, said winding comprising a plurality of spirally wound turns of a rst layer of conducting sheet material and a second layer of insulating sheet material having at least a partial coating of thermosetting resin thereon, the thermosetting resin on said insulating sheet material bonding the turns of said winding together in a unitary assembly.

References Cited by the Examiner UNITED STATES PATENTS OTHER REFERENCES Fiberglas, Catalog No. EL 44-7, 1944, Owens- Corning Fiberglas Corp., Toledo 1, Ohio (24 pp.-particularly page 2l).

JOHN F. BURNS, Primary Examiner.

MILTON O. HIRSHFIELD, Examiner. 

1. A MAGNETIC CORE STRUCTURE COMPRISING FIRST AND SECOND LEG PORTIONS SPACED APART FROM ONE ANOTHER, YOKE PORTIONS CONNECTING THE ENDS OF SAID LEG PORTIONS, EACH OF SAID YOKE PORTIONS COMPRISING A PLURALITY OF LAMINATIONS FORMED FROM MAGNETIC STRIP MATERIAL AND ASSEMBLED IN A RECTANGULAR CONFIGURATION HAVING FIRST AND SECOND OPENINGS THERETHROUGH, EACH OF SAID LEG PORTIONS COMPRISING A PLURALITY OF RING CORE SECTIONS, EACH OF SAID RING CORE SECTIONS INCLUDING A CENTRAL OPENING AND A RADIAL GAP EXTENDING AXIALLY THROUGH SAID SECTION, THE RING CORE SECTIONS OF EACH LEG PORTION BEING ASSEMBLED BETWEEN THE ASSOCIATED YOKE PORTIONS ALONG A COMMON AXIS WITH THE CENTRAL OPENINGS, SUBSTANTIALLY ALIGNED WITH EACH OTHER AND WITH ONE OF THE OPENINGS IN EACH OF SAID YOKE PORTIONS, ANNULAR ELECTRICALLY INSULATING MEMBERS DISPOSED BETWEEN THE ADJACENT RING CORE SECTIONS, EACH INSULATING MEMBER HAVING AN OPENING THERETHROUGH LARGER THAN THE OPENING IN EACH RING CORE SECTION, FIBROUS REINFORCING MATERIAL DISPOSED TO PASS THROUGH THE ALIGNED OPENINGS OF EACH LEG PORTION AND THE ASSOCIATED YOKE PORTIONS, A THERMOSETTING RESIN FILLING THE BALANCE OF THE ALIGNED OPENINGS AND THE RADIAL GAPS OF SAID RING CORE SECTIONS AND THE OPENINGS IN THE INSULATING MEMBERS TO BOND SAID YOKE AND LEG PORTIONS AND SAID INSULATING MEMBERS TOGETHER IN A UNITARY ASSEMBLY, AND SAID RESIN HAVING PROJECTING PORTIONS FORMED AROUND ITS PERIPHERY IN THE OPENINGS IN THE INSULATING MEMBERS. 